Electric current effect on microstructure of ball grid array solder joint

Electromigration of Pb-free solder under a low level of current density

“…The highest current density appears in the corners where the electrons changed orientation. This agrees well with some previous research [2][3][4][5][6][7][8][9][10][11]. In the whole structure, the maximum value of the current density is 1.42 × 10 5 A/cm 2 and the minimum value is 1.97 × 10 2 A/cm 2 (Fig.…”

“…Since the cross-sectional area of the trace in the chip is smaller than that of the solder bump substantial heat will accumulate in the structure, especially at the corner locations where the current flows-in or flows-out. The local temperature rise should not be ignored when very narrow and thin conductors are used to connect the solder bumps during an electromigration test [9][10][11]. Therefore, the reliability of solder interconnection, especially for BGA interconnection integrity, may be susceptible to thermal and electrical degradation under high current stressing.…”

Effect of electromigration on intermetallic compound formation in line-type Cu/Sn/Cu interconnect

“…The effect of EM on the solder joints has been studied [4][5][6][7][8][9][10][11]. Chen and co-workers [4] investigated the effect of moderate electric current density on mechanical properties of Ni-P/Sn-3.5Ag/Ni-P and Ni/Sn-3.5Ag/Ni solder joints and found that the EM caused brittle failure of the solder joints and this tendency for brittle failure increased with increasing current density.…”

“…Chuang and co-workers [7] investigated the EM behavior of Sn-3Ag-0.5Cu and Sn-3Ag-0.5Cu-0.5Ce-0.2Zn solder joints at room temperature with a current density of 3.1 × 10 4 A/cm 2 and found that after dopping with Zn and Ce the EM process of Sn-Ag-Cu solder joints were accelerated due to the refinement of the solder matrix. Zhang and co-workers [8] found an abnormal polarity effect after direct current was applied to the Cu/Sn-9Zn/Cu interconnect, i.e., the IMC at the cathode side was thicker than that at the anode side, which was in contrast to the Cu/In/Cu and Cu/Sn-Pb/Cu interconnects [9,10]. Lin and co-workers [11] investigated the EM behavior of Cu/Sn-8Zn-3Bi/Cu interconnects and found that Bi is the dominant migrating species but Sn and Zn are relatively immobile under EM at 80 • C. The EM behavior is very complicated in solder interconnects, since different effects may be dominant when the current is applied to the different types of solder interconnects at different temperatures.…”

Electrical characterizations and evaluation of thermo-mechanical stresses of a power module dedicated to high temperature applications

“…Indeed, the external connectors solder (Sn95Sb5) present a crack especially induced by the intermetallics growth in Sn solder which finally leads to failure. This failure mode had been presented in various articles about high temperature [4,5].…”